Conventionally, piezoelectric weight sensors, capacitance weight sensors, and the like for detecting load or pressure of an object to be measured are widely known (see, for example, Japanese Patent Laid-Open Publication No. Hei 7-5020).
One conventionally known weight sensor 1 shown in FIG. 6 is generally made up of a rotating shaft 5 vertically supported by a bearing 3 on a stage 2 and driven to rotate by a motor 4, and a scale plate 7 attached to an upper part of this rotating shaft 5.
The weight sensor 1 detects load of an object 6 placed on the scale plate 7 by a weight sensor unit 8 provided below the bearing 3.
With this known weight sensor 1, however, because the load of the object 6 is transmitted to the weight sensor unit 8 through the bearing 3, the sensor was easily affected by mechanical noises of the bearing 3, and high-precision measurement of the load of the object 6 was hard to achieve. When the object 6 is placed offset from the center of the scale plate 7, in particular, the sensor was easily affected by a load that is generated in a horizontal direction due to the sensor structure, resulting in a large measurement error.